Buyer’s Guide to Radiant Cut Diamonds

Love the octagonal shape of an emerald cut but also the sparkle of a round brilliant? Your diamond shape is the radiant cut! This innovative cross between those two more well-known diamond cuts lets you have your cake and eat it too. The radiant cut has straight sides, beveled corners and lots of brilliance. Rectangular or square, colorless or fancy color, radiant cut diamonds are a popular choice for a dazzling engagement ring.

SHOP RADIANT DIAMONDS

The History of Radiant Diamonds

The story of the radiant cut diamond begins in New York in the seventies with diamond cutter Henry Grossbard. Grossbard worked at the cutting wheel with real diamonds, adding facets one at a time to develop an octagonal diamond that had maximum brilliance.

Building on the work of Basil Watermeyer, the South African cutter who invented the Barion Cut, he added triangular pavilion main facets that meet a step cut facet below the girdle. His achievement was a cut that had the elongated rectangular shape of the emerald cut but with all the fire and sparkle of a round brilliant. With its 70 or 66 facets, the radiant is the most brilliant of the square-sided cuts.

Unusually for the time, Grossbard decided to patent his design and registered the brand name before putting it on the market. Later, he created a version of the radiant cut designed to concentrate the color of fancy color diamonds, making yellow, blue, and pink diamonds more vivid.

Over the decades, cutters adjusted the proportions and angles to improve light performance.

For almost two decades, the only radiant cuts you could buy were from Henry Grossbard. The patent has long expired so many cutters now produce versions of the radiant cut. On a GIA grading report, a radiant cut is called a "cut corner rectangular modified brilliant" or a "cut corner square modified brilliant."

Why We Love Radiant Cut Diamonds

There’s something so crisp and modern about the straight edges of a radiant cut. It has excellent fire and brilliance and the facet pattern forms beautiful lines that emphasize the square shape.

The radiant cut has a “crushed ice” or “kaleidoscope” facet pattern, with many facets reflecting each other so it looks like there are even more flashing facets catching the eye.

The radiant is designed for brilliance, not for weight.

Because of its cut corners and flat pavilion facets, radiant diamonds look larger than princess cut diamonds or round brilliant diamonds.

That means a two-carat radiant will look larger than a two-carat princess cut or round brilliant diamond. Only the oval cut looks as large. Look at the five two-carat diamonds below and see which shape looks the largest to you.

How to Buy Radiant Cut Diamonds

Ready to buy a radiant? Because radiant diamonds are less common than round brilliants, many retailers won’t have any in stock. You are much better off buying fancy shapes like this online because you’ll have a much better selection in your target color, clarity and carat weight so you can assess the shape and cut quality and pick a really beautiful diamond that’s a good value too.

You’ll be able to select a better radiant cut diamond if you buy it loose rather than already set into an engagement ring.

It’s important to rely only on diamond grading reports from GIA or AGS, the world’s most respected diamond grading laboratories. You can’t rely on the grades from other labs to be equivalent.

The basics of the 4Cs of diamond quality are the same as for round brilliant diamonds but your AGS or GIA grading report won’t include a cut grade. Because of its internal reflections, the radiant cut can concentrate color so you may want to select a slightly higher color grade for a radiant cut diamond. But the many facets of the radiant are good at camouflaging inclusions so you will be able to trade down one clarity grade.

Not all radiant cut diamonds look alike. A radiant can be square or rectangular depending on its length to width ratio.

A ratio of 1 would be a square and a ratio of 1.75 would be a long thin rectangle. Which you prefer is up to you: most people look for something in the middle.

Make sure you buy your loose radiant cut diamond from a company that demonstrates a commitment to responsible sourcing. Supporting the Kimberley Process is a great start but the best suppliers go beyond that, sourcing diamonds directly from sightholders and mines.

There’s one final step to making sure that you’ve found the right radiant cut diamond. Compare your diamond by entering the GIA report number into ROSI. In a few seconds, you’ll see if artificial intelligence can find you a better diamond value. You may find a higher-rated diamond at the same price or a similar stone for a lower price. If not and your diamond passes the A.I. Challenge, you know you are really getting a great deal.

What ROSI Recommends

Buying radiant cut diamond online is more challenging than shopping for a round brilliant because there are more radiant cuts that aren’t well-cut. That’s why we created ROSI, an artificial intelligence personal shopping tool powered by IBM’s Watson: to sort through all the radiant diamonds available on the market to find the best balance of quality and value for your budget, eliminating all the diamonds that don’t live up to our high standards. Thanks to ROSI, you can find the best radiant cut diamond for your budget in one single step.

ROSI generally recommends a color of G and clarity of VS2 for radiant diamonds. This will give you a diamond that looks colorless with no inclusions visible to the naked eye. The money you save can be invested in a larger size diamond and a better cut. ROSI recommends excellent symmetry and polish for a diamond that sparkles beautifully.

ROSI recommends radiant cut diamonds with a rectangular length to width ratio of 1.25 to 1.50.

Round Brilliant Quality Checklist

  • Color: G-H
  • Clarity: VS2-SI1
  • Symmetry: Very Good-Excellent
  • Polish: Very Good-Excellent
  • Depth: 58%-65%
  • Table: 56%-64%
  • Length to width ratio: 1.5 to 1.75

The cut quality of a radiant cut diamond depends on its angles and proportions. Large depth and table percentage like these ranges will include combinations that work well together and combinations that don’t. ROSI looks for diamonds with the best combination of depth and table percentages to reflect the maximum light back to the eye as brilliance.

Radiant Cut Diamonds vs Princess Cut Diamonds vs Cushion Cut Diamonds

The two other options that are most similar to a radiant cut diamond are the princess cut diamond and the cushion cut diamond.

Princess cut diamonds have straight sides like a radiant cut but they have a square outline without the beveled corners. The sharp corners are more unique but they also can be prone to chipping. The differences go beyond the outline: the radiant has many more pavilion facets than the princess cut diamond, adding more scintillation and fire and chaotic brilliance rather than the princess cut’s defined X-facet pattern. The princess pavilion is deeper, making it look a bit smaller from above.

A cushion cut diamond is another option for those who love the radiant cut. A cushion cut can display the same crushed ice many- faceted look of the radiant. Instead of the radiant cut’s straight sides and cut corners, a cushion has rounded sides and corners. The best cushion cuts will display the hearts and arrows pattern in a light-performance viewer. A hearts-and-arrows cushion like RockHer’s Cushion Brilliant designed by master cutter Brian Gavin, is a great way to get the precision cutting and high light performance of a hearts and arrows round brilliant for less per carat.

Best Radiant Cut Engagement Ring Styles

Our customers’ favorite setting for radiant diamonds is a simple radiant diamond band engagement ring. Halo engagement rings are also popular because they make your radiant cut diamond look larger thanks to the frame of diamonds around it. The geometric style of a radiant cut goes well in a bezel-set solitaire engagement ring. In a radiant three stone engagement ring, our customers generally or tapered baguettes on the side.

You’d be surprised how far your money can go shopping for a radiant diamond engagement ring online.

Pave Band

Kelly

Halo Engagement Ring

Alannah

Solitaire Bezel

Hayley

Tapered Baguette

June
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